In the production and/or processing of material webs the demand for an improvement in productivity leads to higher and higher production outputs of the apparatuses used and as a consequence thereof also to higher and higher speeds of the material webs and/or higher machine speeds.
Forces acting on a material web which at low speeds do not yet constitute a problem lead at high speeds to phenomena such as flapping of the material web, for example, and as a result cause said material web to tear. Such uncontrolled and undesirable tears always result in machine downtime and consequently in a production outage. A further problem in connection with tears of said kind is that the material web runs out of control through the apparatus or a subsection of the apparatus if the occurrence of tearing is not detected quickly enough.
In order to enable the cause of a material web tear to be analyzed, first analysis devices are currently being deployed which utilize, inter alia, laser scanners, video systems, photoelectric sensors, tear detectors, etc. The documents DE 42 16 653 A1 and DE 42 16 653 A1, for example, disclose methods and first analysis devices for detecting tearing of a material web.
Reliable detection of tears is not the only requirement, however. Regular quality controls and continuous acquisition of other measurement and influencing variables which affect the production and/or processing of a material web are also necessary. Various other analysis devices are provided for that purpose.
To be cited as typical examples of apparatuses for the production and/or processing of material webs, e.g. consisting of paper, cardboard, plastic film, metal foil, textiles or composites comprising two or more of said materials, are, inter alia, paper machines, presses, calenders, rotary punching machines, rotary cutting machines, and the like.
There are thus available to the operator of an apparatus for producing and/or processing a material web signals supplied by the various first and further analysis devices for performing state and process monitoring in the region of the apparatus.
Correlating different signals with one another, in particular more than two signals, is proving to be difficult at the present time. Measurement and influencing variables that are attributable to the operator of the apparatus, environmental factors and so forth are likewise difficult to correlate with one another and with signals in relation to tear detection.